Can ranitidine be administered intramuscularly (IM)?

Intramuscular Administration of Ranitidine

Yes, ranitidine can be administered intramuscularly (IM) at a dose of 50 mg every 6 to 8 hours as indicated in the FDA drug label. 1

Administration Routes and Dosing

Ranitidine can be administered through multiple parenteral routes:

• Intramuscular (IM) injection: 50 mg (2 mL) every 6 to 8 hours with no dilution necessary 1
• Intravenous (IV) injection: 50 mg every 6 to 8 hours, diluted and administered as either:
  • Intermittent bolus: Diluted to concentration ≤2.5 mg/mL, injected at rate ≤4 mL/min
  • Intermittent infusion: Diluted to concentration ≤0.5 mg/mL, infused at rate of 5-7 mL/min
  • Continuous infusion: Delivered at rate of 6.25 mg/hour 1

Clinical Applications

Ranitidine IM administration is particularly useful in:

1. Anaphylaxis management: Guidelines recommend ranitidine 50 mg in adults and 12.5 to 50 mg (1 mg/kg) in children as adjunctive therapy to epinephrine. For anaphylaxis, ranitidine may be diluted in 5% dextrose to a total volume of 20 mL and injected intravenously over 5 minutes 2

2. Hospitalized patients with:

   • Pathological hypersecretory conditions
   • Intractable duodenal ulcers
   • Patients unable to take oral medication 1

3. Preoperative settings: To reduce the risk of pulmonary aspiration, though evidence for this indication shows variable results for gastric pH and volume 2

Important Considerations

• Pharmacokinetics: Ranitidine is absorbed very rapidly after IM injection, with mean peak levels of 576 ng/mL occurring within 15 minutes or less following a 50 mg dose 1

• Bioavailability: Absorption from IM sites is virtually complete, with a bioavailability of 90% to 100% compared with intravenous administration 1

• Special populations:

  • Renal impairment: For patients with creatinine clearance <50 mL/min, the recommended dosage is 50 mg every 18 to 24 hours 1
  • Pediatric patients: Total daily dose of 2 to 4 mg/kg, divided and administered every 6 to 8 hours, up to maximum of 50 mg every 6 to 8 hours 1

Safety Profile

Ranitidine is generally well-tolerated with infrequent serious adverse effects. However, clinicians should be aware of:

• Anaphylaxis risk: Though rare, ranitidine-induced anaphylaxis has been reported, particularly with IV administration 3
• Cardiovascular effects: Extremely rare cardiovascular side effects (approximately 1 in 1 million patients) have been reported, primarily sinusal bradycardia and atrioventricular blockade, especially after rapid IV administration 4

Clinical Pearls

• When using ranitidine for anaphylaxis management, remember it is considered second-line therapy to epinephrine and should never be administered alone in anaphylaxis treatment 2
• In combination with diphenhydramine, ranitidine is superior to diphenhydramine alone for anaphylaxis management 2
• For patients with cross-sensitivity concerns, skin testing can help determine if there is cross-reactivity with other H2-receptor antagonists 3

Ranitidine IM administration provides a valuable alternative when oral or IV routes are not feasible, with comparable bioavailability to IV administration and a well-established safety profile.